Yeah, basically I want to change from a 16-bit system to a 32, (later 64 when it will work) but it does not work. Nasm didn't give me an error, but it doesin't run in virtualbox. Here is a link if someone understands assembly:
https://github.com/Xulum12/assembly/blob/main/boot2.asm
[org 0x7c00]
GDT_Start:
null_descriptor:
dd 0
dd 0
code_descriptor:
dw 0xffff
dw 0
dw 0
db 10011010
db 11001111
db 0
data_descriptor:
dw 0xffff
dw 0
dw 0
db 10010010
db 11001111
db 0
GDT_end:
GDT_Descriptor:
dw GDT_end - GDT_Start - 1
dd GDT_Start
CODE_SEG equ code_descriptor - GDT_Start
DATA_SEG equ data_descriptor - GDT_Start
cli
lgdt [GDT_Descriptor]
mov eax, cr0
or eax, 1
mov cr0, eax
jmp CODE_SEG:stpm
[bits 32]
stpm:
mov al, 'q'
mov ah, 0x0f
mov [0xb8000], ax
times 510-($-$$) db 0
db 0x55, 0xaa
CodePudding user response：
Your code starts with data. CPU treats data as instructions which can do unexpected things. You need to either move data to end of the code, or add a JMP instruction at the beginning of the code that skips the data bytes.
CodePudding user response：
Some reasons why it fails include:
- The data gets executed as if it was code
- The descriptors have 9 bytes instead of 8
- The segment registers have not been setup
- There's no decent end for the code
- ...